Early Embryonic 1 Flashcards
What is clevage?
30 hours after fertilaisation Zygote divides into 2 blastomeres, these keep dividing to form the morula a ball of cells
Define the pre-embryonic, embryonic and fetal stages
0-2,2,8,9-38
What is compaction?
Differentiation of morula into blastocyst with inner cell mass (embryoblast) and outer cell mass (trophoblast)
What is the zona pellucida?
Glycoprotein shell to prevent polyspermy, disappears on day 5
Discuss week 1
Development from zygote to morula via clevage
Morula to blastocyst via compaction
Hatch from zona pellucida
Totipotent - pluripotent
Now 107 cells - 8- embryo, 99 - fetal membrane
Discuss week 2
Differentiation of embryoblast into epi and hypoblast
Trophoblast into syncitiotrophoblast and cytotrophoblast
Forms bilaminar disc and amniotic cavity
Implantion
Formation of primitive yolk sac by heusers membrane
Primitive yolk sac pulled away from cytotrophoblast
Maternal sinusoids join with syncitiotrophoblast
Formation of secondary yolk sac
Formation of chorionic cavity by fusion of spaces in extraembryonic mesoderm
Define blastocyst
Formed when morula undergoes compaction has inner cell mass(embryoblast) and outer (trophoblast)
describe the trophoblast
r cell mass, from support structures for embryo
describe the embryoblast
inner cell mass107 cells 8 go onto form embryo
describe the syncitiotrophoblast
derivative from trophoblast, cells that invade maternal sinusoids resulting in uteroplacentalirculation
describe the cytotrophoblast
derivative of trophoblst, placental membrane ound yolk sac